cmd/link: skip TestDWARF when cgo is disabled

While we're here, fix a Skip/Skipf error I noticed.

Fixes #19796.

Change-Id: I59b1f5b5ea727fc314acfee8445b3de0b5af1e46
Reviewed-on: https://go-review.googlesource.com/38992
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

2 files changed, 20 insertions, 0 deletions

diff --git a/src/internal/testenv/testenv.go b/src/internal/testenv/testenv.go
index 4cd8a2b541..1a13ac3f2b 100644
--- a/src/internal/testenv/testenv.go
+++ b/src/internal/testenv/testenv.go
@@ -151,6 +151,15 @@ func MustHaveExternalNetwork(t *testing.T) {
 	}
 }
 
+var haveCGO bool
+
+// MustHaveCGO calls t.Skip if cgo is not available.
+func MustHaveCGO(t *testing.T) {
+	if !haveCGO {
+		t.Skipf("skipping test: no cgo")
+	}
+}
+
 // HasSymlink reports whether the current system can use os.Symlink.
 func HasSymlink() bool {
 	ok, _ := hasSymlink()
diff --git a/src/internal/testenv/testenv_cgo.go b/src/internal/testenv/testenv_cgo.go
new file mode 100644
index 0000000000..e3d4d16b33
--- /dev/null
+++ b/src/internal/testenv/testenv_cgo.go
@@ -0,0 +1,11 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build cgo
+
+package testenv
+
+func init() {
+	haveCGO = true
+}